<?php
/*
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This software consists of voluntary contributions made by many individuals
 * and is licensed under the LGPL. For more information, see
 * <http://www.doctrine-project.org>.
 */

namespace Doctrine\ORM\Id;

use Doctrine\ORM\EntityManager;

/**
 * Id generator that uses a single-row database table and a hi/lo algorithm.
 *
 * @since   2.0
 * @author  Benjamin Eberlei <kontakt@beberlei.de>
 * @author  Guilherme Blanco <guilhermeblanco@hotmail.com>
 * @author  Jonathan Wage <jonwage@gmail.com>
 * @author  Roman Borschel <roman@code-factory.org>
 */
class TableGenerator extends AbstractIdGenerator {
	private $_tableName;
	private $_sequenceName;
	private $_allocationSize;
	private $_nextValue;
	private $_maxValue;
	
	public function __construct($tableName, $sequenceName = 'default', $allocationSize = 10) {
		$this->_tableName = $tableName;
		$this->_sequenceName = $sequenceName;
		$this->_allocationSize = $allocationSize;
	}
	
	public function generate(EntityManager $em, $entity) {
		if( $this->_maxValue === null || $this->_nextValue == $this->_maxValue ) {
			// Allocate new values
			$conn = $em->getConnection();
			if( $conn->getTransactionNestingLevel() == 0 ) {
				
				// use select for update
				$sql = $conn->getDatabasePlatform()->getTableHiLoCurrentValSql( $this->_tableName, $this->_sequenceName );
				$currentLevel = $conn->fetchColumn( $sql );
				if( $currentLevel != null ) {
					$this->_nextValue = $currentLevel;
					$this->_maxValue = $this->_nextValue + $this->_allocationSize;
					
					$updateSql = $conn->getDatabasePlatform()->getTableHiLoUpdateNextValSql( $this->_tableName, $this->_sequenceName, $this->_allocationSize );
					
					if( $conn->executeUpdate( $updateSql, array( 1 => $currentLevel, 2 => $currentLevel + 1 ) ) !== 1 ) {
						// no affected rows, concurrency issue, throw exception
					}
				} else {
					// no current level returned, TableGenerator seems to be broken, throw exception
				}
			} else {
				// only table locks help here, implement this or throw exception?
			// or do we want to work with table locks exclusively?
			}
		}
		return $this->_nextValue++;
	}
}